Bleach: Season 13, Episode 256
While Byakuya allows his squad to hold a sakura viewing party at his mansion, two strange attackers arrive, but one of them is quickly defeated by Sode no Shirayuki and Senbonzakura, who have since rematerialized, while the other escapes. Captain Kurotsuchi refers to these attackers as "Sword Fiends", which are zanpakuto who have killed their masters. Rukia and Sode no Shirayuki try lure out the other by having a drinking party, but fail. Soon Rukia and Sode no Shirayuki find the sword fiend attacking and defeat him together, capturing him and turning him in for study. Captains Ukitake and Kyoraku become concerned at this development, noting that the Seireitei is still being rebuilt.